1. Origin of Invention
This invention disclosure described herein was made under Department of Energy Contract No. DE AC2180MC14593.
2. Technical Field of the Invention
This invention relates to high temperature heating apparatus. More particularly, this invention relates to high temperature heating for use in heating samples for spectroscopic studies, such as electron spin resonance measurements.
3. Background
The measurements of electron spin resonance or nuclear magnetic resonance desirably includes measurements at elevated temperatures, i.e. as high as 1000.degree. C. Such high temperature measurements, however, are complicated by the need to elevate the sample to a high temperature while maintaining the surrounding cavity within the magnetic field at a much lower temperature; preferably as close to ambient as possible.
It has been proposed, in the past, to thermally isolate and insulate the sample from the surrounding cavity by a cylindrical dewar. For example, Shoolery U.S. Pat. No. 2,864,995 discloses the heating of a gyromagnetic resonance sample for nuclear magnetic resonance spectroscopy analysis using an evacuated cylinder to transport heated gas from a remote source to the sample mounted in the nuclear magnetic resonance spectrometer.
Typically, however, such devices are limited in temperature due, in part, to the deterioration of radiation heat shielding such as deposited films of silver or platinum, which tend to migrate or react with the walls of the quartz envelope at high temperatures, i.e. over 400.degree. C. Furthermore, at temperatures above 400.degree. C., gases released from the quartz envelope tend to limit the life cycle of the dewar to about 25 hours before re-evacuation becomes necessary.
It would, therefore, be desirable to provide a sample heating apparatus capable of operating at temperatures of 400.degree.-1000.degree. C. over an extended period of time without serious loss of vacuum or destruction of the radiant heat shield surrounding the heater. It would also be desirable to provide a sample heating apparatus having a radiant heat shield with a stable reflective surface.